Process variations, and voltage and temperature variations are uncontrollable factors that can degrade the performance, power, area, and yield of integrated circuits. In order to design circuits with acceptable power, performance, area and yield, circuit designers must manage these variations on large circuits, in aggressive time schedules. “Variation-aware” tools aim to help designers with these goals, and include Monte Carlo samplers, and many more advanced tools.
Currently available variation-aware design tools are unable to handle: (a) statistical process variation, (b) voltage, temperature, and other uncontrollable factors in the circuit's operating environment (“environmental variation”), (c) very large circuits, which are often hierarchically organized, (d) circuits with a very low probability of failure, and (d) hundreds, thousands or more voltage and temperature (VT) corners.
Therefore, improvements in variation-aware design tools are desirable.